In orthogonal frequency division multiplexed (OFDM) and orthogonal frequency division multiple access (OFDMA) systems, a remote client station achieves its synchronization status with respect to a base station by detecting and synchronizing to a training sequence, also known as a preamble. Usually appearing at the beginning of transmission frame, the preamble is a particular pseudo-noise (PN) sequence among a set of PN sequences known a priori to the client station.
In some OFDM-based broadband wireless technologies, preamble has some frequency or time properties that can facilitate its detection in a client station. For example, in the IEEE 802.16d/e standard, known commercially as WiMAX™, preamble occupies every third tone or subcarrier, leaving other tones unused. In the frequency domain, this property makes the representation of the preamble in the time domain have repetitive characteristics.
There is room for improving the efficiency of detecting the sequence of a wireless signal, whether a preamble sequence, ranging sequence, sounding sequence or other sequence having a predetermined pattern.